Special occasional publication

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31

HARVARD UNIVERSITY

Ernst Mayr Library

of the Museum of

Comparative Zoology

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THE SYSTEM OF THE ORDER GEOPHILA (=HELICIDA) (GASTROPODA PULMONATA)

BY

A. A. SCHILEYKO

Zoological Institute

Academy of Sciences

Leningrad , USSR

IN

MORPHOLOGY. SYSTEHATICS AND PHYLOGENY OF rOLLUSKS

Transactions of the Zoological Institute
Academy of Sciences, USSR, Vol. 80, pp. kh-69 , 1979

An edited translation of:

Sistema Otryada Geophila {=Helicida) (Gastropoda Pxilmonata)
Morfologiya, Sistematika i Filogeniya Mollyuskov
Trudy Zoologicheskogo Instituta, Akademiya Nauk SSSR
Tom 80, pp. l+U-69, 1979

RY

KENNETH J. BOSS AND MORRIS K. JACOBSON
Museum of Comparative Zoology
Harvard University
Cambridge, Ma. 02138

Special Occasional Publication

NO. 6

published by the

Department of Mollusks

Heirvard University

Cambridge, Massachusetts 02136

1985

THE SYSTEM OF THE ORDEE GEOPHILA (=HELICIDA) (GASTROPODA PULMONATA)

A. A. Schileyko

Generally speaking the fewer the characteristics employed as
bases for the systematics of any group of animals, the more consis-
tently harmonious that taxonomic scheme seems to be. When using numerous
characteristics relating to particular organs or structures, one often
elaborates a less harmonious, though more synthetic, system because
certain groups of features fail to correspond to others. Also the
more adequate system is strengthened by the utilization of a holistic
approach wherein the various morphological systems are viewed as inter-
related parts of an organic whole, the result of the dynamic forces
of evolution. At higher taxonomic ranks, the indicators of evolutionary
and developmental pathways of the various organs and structures take
on greater significance.

T\irning our attention to the current systematics of the Order
Geophila, we recognize that attempts to understand their phyletic
relationships have fallen short of a holistic analysis. Reduction of,
and substitution for, one organ by another has been frequent while
problems of parallelism and convergence have often been insufficiently
appreciated. Only through a more thorough analysis of such phenomena,
including a study of variation between species and among genera as
well as the discernment of evolutionary pathways will a more com^pre-
hensive, phyletically accurate system emerge.

Various opinions of the systematics of the order exist. Most
specialists accept the one proposed by Pilsbry (l900) which is based

on the characteristics of the structTxre of the excretory apparatus; and
he divides the order into 3 suborders: Orthiirethra , Heterurethra,
and Sigmurethra. Later a fourth group, Mesurethra, was added by Boettger
(195U) who shared Pilsbry's opinions. Solem (1959) proposed a phylogenetic
system based on the unconnected branches Orthurethra, Sigmurethra, Mesurethra,
and Tracheopulmonata plus Heterurethra. Thiele's system (l93l), based
primarily on conchological features, has often been subjected to criticism
from the point of view of the anatomist, although the validity of many of
Thiele's formerly rejected arguments should now be recognized. The system
proposed by Wenz & Zilch (Zilch, 1959-196o) is a compilation in which
Thiele's system, modified to conform to newly accumiilated facts (between
193i+ and 1959), was superimposed on Pilsbry's earlier scheme. The most
widely currently accepted arrangement is the one proposed by Taylor &
Sohl (1962), where the same suborders appear, divided into 19 superfamilies.

Moreover, the largest group, Sigmurethra, was divided by H.B. Baker,
following Pilsbry, into the infraorders , Holopoda and Aulacopoda, plus a
new infraorder, Holopodopes. The members of these groups are distinguished
by the nature of furrows or grooves in the foot. In Holopoda and Holopodopes

Heterurethra as understood by Pilsbry includes 3 independent groups
(accorded ordinal rank by Soviet malacologists) : Succineida, Aylliida,
Athoracophorida (Minichev, 1971; Minichev & Starobogatov, 1975; Slavoshevskaya,
197I; Van Mol, I967). For this reason the early groups of Heterurethra
will not be treated here.

the peripedal fiirrow runs along the margin of the sole or slightly above
it, the sole itself always being entire. In Aulacopoda the peripedal furrow
is placed noticeably higher than the margin of the sole and the sole itself
is often divided by 2 parallel furrows. The obstacle to uniting Holopodopes
and Holopoda lies in the fact that Baker assigns them to different phylo-
genetic branches: the first is lower than Sigmurethra, the second is higher.

Hence up to the present, three groups of characteristics have been
proposed as suitable bases for the construction of a system for the order
Geophila: conchological , excretory, and pedal. In addition, the sexual
apparatus has been used in diagnosis at the familial or generic levels.
We plan to examine separately a series of groups of characteristics; to
simplify matters, we will limit ourselves to the discussion only of the
system which we here propose.

We are certain that those of our colleagues who are also interested
in the systematics of the Geophila will offer corrections on the basis of
new facts: nevertheless, the author is convinced of the validity of the
basic classification here offered.

THE SHELL

It is commonly admitted that conchological featiires in general
possess only little taxonomic value and that the area of their applica-
tion is limited to the familial level, and more often to the generic
or specific levels. Thotigh partly true, there are some shell features
which possess a considerahly greater informative value which permits
their use at higher taxonomic ranks. The general appearance of the
shell, as well as the presence of longitudinal parietal and columellar
plates, are such characteristics. Naturally, when we speak of the general
shell shape, we do not include the numerous secondary modifications .

The first problem to present itself in our investigation concerned
the nat;ire of the original Geophila shell. If we assume that the order
derived from ellobiid-like ancestors — ^both fossil and Recent Ellobiidae
are characterized more or less by a monotypic shell of elongated form
with columellar and parietal plates — then we must accept such a shell
type as the original shape. This almost \iniversally accepted opinion
is reinforced by the fact that the ancient (and although, in our opinion,
only distantly related) Partulidae and Achatinellidae do indeed possess
precisely such a kind of shell; in fact, that shape is characteristic
for the lower Orthurethra as well as for the lower non-orthurethrous
Geophila. At first glance, serious deviations from this shell type among
the lower Geophila are seen in Pupilloidea and Sagdoidea: i.e. the
Pyramidulidae , Valloniidae, Strobilopsidae, Sagdidae, and Thysanophoridae.
However, the microhelicoid shells, characteristic for the families cited,
are "inscribed" in the beginning as bulimuloid shells, which, in combina-
tion with anatomical f ^atiires , give testimony to the origin of those
families by means of the early sexual maturity of the ancestral form.

and consequently in the early interruption of shell growth. The appearance
protandry (e.g. in the Valloniidae) , which leads to the swift reduction of the
male genital system after having performed its function, is another consequence
of the change of the bulimuloid shell to the microhelicoid.

In the almost limitless variations of the shell of the Geophila, one can
detect several evolutionary lines. To complete the survey of the lower mem-
bers of the order, we note a tendency toward reduction of the parameters and
retention of the same proportions (e.g. Pupillidae, Cionellidae, Vertiginidae ,
and Orculidae). This tendency is bound up with life in microhabits , often —
but by no means always — in climatic conditions of sharp daily temperature
changes .

The other tendencies fit in with the natural groupings, that is, with
the suborders proposed in the present work. Thus high, many-whorled shells,
characteristic of most of the Achatinidae may reach a very large size in a
moist tropical climate. The inhabitants of forest, and secondarily of moun-
tains, often crawl on vertical surfaces and frequently with the ventral side
upward and evolved a long narrow shell shape ( Clausilioidea) . The columellar
plates in such cases may grow stronger since they are the point of support for
the columellar muscle and they facilitate the evolutionary direction of shell
shape (Likharev, 1962).

In the lower Oleacinina, the shell initially is of the same type, but
members of this suborder inhabit a large number of biotypes and this explains
the heterogeneity of their shells. The greatest degree of this is seen in the
Streptaxidae, among which can be fo\ind almost all types of shell shape seen
in the Geophila (Zilch, I961), and above all, in the unique shell type of
Gonaxis with its displaced or distorted axis. The Oleacinidae possess several
unique shell features , rarely encountered elsewhere than in the suborder

Oleacinina: the aperture is high and narrowed in its upper angular part and
is not expanded laterally: the combination of such an aperture with strongly
flattened whorls and weak sutures gives the shell a bullet-like shape, thus
enabling the animals to crawl in the soil in their hunt for oligochetes, their
basic food. The angular area of the apertural region is an adaptive feature:
in this region the pneumostome is displaced and the mollusk can breathe freely
while the anterior part of the body is buried under the solid surface. Charac-
teristically, a similar shell is encountered in those members of other sub-
orders which are also closely boimd up with the soil. It is enough to observe
that a predatory life style in the Oleacinina brings about a tendency to shell

reduction as in the case of two other higher suborders, the Helixina and the

,. . (1)
Limaxma.

Shell reduction itself proceeds along two evolutionary pathways associated
with either l) the widening of the last whorl and consequently of the aperture,
or 2) the increasing of the relative height of the aperture. The reduction of
the shell may proceed either through a regularly whorled spiral of the shell
or a regul.ar reduction of the spire. In the Helixina the attainment of the slug
shape proceeds along the first path: this process can in detail be followed
in the Vitrinoidea. Among the Oleacinina, the Testacellidae , however, lose
their shells by passing through a "succinoid" stage. The increase of the re-
lative apertioral height can be traced in some New World Oleacinidae: Euglandina
flammulata H.B.B. — Pittieria arborea H.B.B. — Euglandina pupa H.B.B. — E. deli-
catula (Shuttl.) — E. saxatilis H.B.B. — Oleacina camerata H.B.B. (Baker,
19^1) — Strebelia berendti (Pfr.). In the first few of these species the
aperture height is 35 0/0 of the shell height, in the last it is 93 0/0; that
is, the aperture is barely shorter than the shell.

To distinguish them from the generic names Helicina and Limacina.

Similarly in the lower suborders (Achatinina, Oleacinina, and Pupillina)
together with a high shell, there is also the presence of coliomellar plates
which may either disappear or grow stronger and more involved. The truncated
columella in the Oleacinidae, Cionellidae, and many Achat inellidae, etc. comes
about as the result of the reduction of the lower part of the columella below
the plates: the lower columellar margin in this case corresponds precisely
to the columellar plates .

The apertural plates mentioned above consist of contrasting basal and pala-
tal elements. The fact is that these two groups of apertiiral formations have
a different historical natxire, different taxonomic importance, and different
functions.

As far as the basal and palatal folds are concerned, they repeatedly and
independently originated in all the suborders which are themselves characterized
by a large degree of diversity and variability even within individual species.
Their role in the final analysis is related to the narrowing of the opening of
the aperture. Their beginning is bound up with the narrowing of the last whorl
before they reach their definitive state. As a result of this narrowing the
secretionary surface of the mantle is reduced by folding, and the formation
of the folds leads to the origin of the apertural armature.

A greatly complicated matter is seen in the colijmellar and parietal ele-
ments. We emphasize the fact that there is no important distinction between
them: in many ellobiids the boundary between the columellar and parietal aper-
tural margins is indistinct and there are not one but many columellar plate-
lets (appearing, apparently, as a result of the fracturing of one of them) by
which the upper columellar plates actually rest on the parietal wall. In con-
trast to the basal-palatal formations, originating either at the very end of
postembryogenesis , or several times in the course of the life of the mollusk

(Schileyko, I96T) , the columellar parietal plates appear even in embryo-
genesis and continue to lengthen as the shell grows. Apropos the origin of
the plates, it may be thought that the single origin of the plates is a con-
sequence of the heterogeneity of the ellobiid ancestral shell. Such hetero-
geneity is actually present in some ellobiids. It is understood that because
of the "break" in the columella at the jimction of the embryonic and defini-
tive whorls, an oblique fold appears, which extends, as the shell is growing,
to the aperture.

The special function of the col\jmellar plates apparently consists in serving
as a support for the columellar muscle. In cross section it is seen that this
muscle rests on the upper surface of the plate: if there are 2 plates, the
muscle lies between them; when there are more than 2 the muscle breaks up early
into branches, each of which occupies a niche between 2 neighboring folds. The
latter condition can be seen, for instance, in the Urocoptidae which have re-
latively small bodies and thus the problem of the narrow shell is especially
severe. Under such conditions the columellar muscle allows the shell to con-
tinue to grow in the set direction.

The principle role of the pariental plate is to force itself into the
mantle cavity and incompletely divide it into right and left halves. We re-
call that the vascularization of the right and left halves of the lung is
different: the respiratory inflow first enters the left half of the cavity
and leaves it through the right: thus the character of the gas exchange
along the entire plane is not equal. Apparently the more primitive division
of the pulmonary cavity was brought about to regulate the air current and to
increase the effectiveness of breathing — a creation of the incompletely
formed partitions. Later such a method of dividing the lung gave way to a
more perfect, active, and sensitive method with the help of the mantle folds

in aquatic Basommatophora (Sullivan & Cheng, 197^), the Helixina, the
Limaxina and thus, independently, in the remaining higher suborders of
the Geophila.

In contrast to the Achat inina, Oleacinina, and Pupillina, the shell
of the Helixina and Limaxina was originally depressed and had a wide um-
bilicus as often found in the Geophila. However, a wide unbilicus is
not a peculiar phenomenon among the Geophila; it usually is not seen in
mollusks with a shell diameter of more than 1 cm, and animals with such
a shell live in strongly shaded areas. In similarly shaped shells the
relative area of the surface is large and its usable volume is small
with a large umbilicus (Fig. LA.) . While as the umbilicus narrowed, the
volume which was taken up by the columellar cavity was "given over" to
the accommodation of the internal organs (Fig. IB). The usual mode for
the narrowing of the umbilicus was through the widening of the whorls ;
at times only the body whorl grew wider and thus the interior of the
shell remained a cavity in commimication with the interior narrow umbilical
aperture.

The columellar parietal plates in some African and Pacific Endo-
dontidae are not homologous to those of the Achatinina, Oleacinina, and
Pupillina which are formed at the end of post-embryogenesis ; they may
originate conver gently.

Many Helixina possess thick-walled, trochid-shaped or spherical shells
of a helicoid appearance without any apertural armature; however, in such
cases, when the apertxiral teeth are present, the area in which they appear
is limited to the aperture and the adjacent section of the parietal wall:
they do not run along the columella or the parietal walls to any distance

inside the shell. Further in this suborder there exists a tendency to a
thinning of the shell, and the repeated appearance, within the suborder,
of the slug form.

10

THE RENOPERI CARDIAL COMPLEX

We have already discussed the data and elatorated on the taxonomic
and evolutionary significance of the renopericardial complex (Schileyko,
1976 a; see also Minichev & Starohogatov, 1971). We will therefore here
discuss only the basic proposals.

In embryogenesis at a stage comparable to the veliger, sigmurethry
is a feature even in orthurethral forms with both having the urethras as
open furrows. Basically in the Orthurethra the kidney differs from the
kidney of related Geophila only because of its greater length. In the
more progressive groups the processes of the shortening of the kidney and
the closing of the urethra take place as an evolutionary parallelism that
is not necessarily synchronous. The suborder Pupillina as here proposed,
differs from the Orthurethra only in excluding the Partulidae and includ-
ing the Sagdoidea. In other words, the Orthurethra is basically a natural
taxon but contrasting it with other entities at the same rank on the
basis of the excretory apparatus is not justified.

The Heterurethra evolved as a result of the decrease of shell size
and the consequent shortening and widening of the lung. Here the kidney
tiirns either clockwise or counter-clockwise and squeezes itself into the
posterior wall of the mantle cavity, finally becoming buried inside the
visceral sac.

In these ways the featixres of the renopericardial complex offer
good data for reconstructing the phylogenetic relationships in super-
families, families, and sometimes genera, but they are not suitable as
basic characteristics for suborders.

11

THE PEDAL INCISIONS

The positions of the longitudinal grooves in the foot are used for
the classification of only the higher Geophila — the Sigmurethra. If
one takes the order as a whole, then in the Achatinina, Oleacinina, and
the majority of Pupillina the foot is of the holopod type and only in
some Helixina and Limaxina is it aulacopod.

In the present article we designate the furrows rimning along the
sole as the pedal furrows, those r-unning along the edge of the sole as
peripedal furrows, and those on the lateral surface as suprapedal furrows.

What is the function of the furrows? The pedal furrows, seemingly
facilitate the intensification of movement by strengthening the functional
loading of weight on the centrail field of the foot; waves of muscular con-
traction in this case move along the central field. The peripedal and supra-
pedal furrows are channels along which, with the aid of a ciliary epi-
thelium, mucus is driven and thus they perform varied protective functions.
It is natural that such furrows are formed as a result of life in arid con-
ditions, and, in the ancestral aquatic shape, permanent furrows were absent
in the foot . The first furrows which appeared in the dry-land forms were
small longitudinal riffles, issuing from below the buccal flap and reach-
ing the anterior half of the body (e.g. Partulidae, Fig. 2, I, II). Later
one of these is fractured into a ring-shaped peripedal furrow, occupying
an extremely lateral position (e.g. Ceriidae, Subulinidae, Clausiliidae ,
Pupillina (Partly), Helixina (Fig. 2, III) or a suprapedal furrow (Vitrea,
Fig. 2, VIIl). One at times may think that the suprapedal furrow is dis-
placed and thus moves to an extreme marginal position (Fig. 2, from VIII
to III) .

12

The pedal furrows are usually homologous (in their derivation) to
the primary suprapedal or peripedal furrows. The only exceptions are
those very rare cases when a single medial pedal furrow appears ( Zoni-
toides , Rhytida, Fig. 2, VI, VII) which originates in a fold in the foot
caused when the animal draws itself into its shell and thus it becomes
isolated (Schileyko, 19T2a) .

Historically the succeeding furrows often appear later than the
first pair of peripedal furrows, and, as the first pair "slips down" to
the sole, they occupy their place (Fig. 2, from III to IV to V and from
VIII to IX to IV to V).

At the same time a second way leading to the origin of the tripartite
division of the sole is conceivable: namely as a consequence of the in-
crease of weight on the central part of the holopod sole. Thus, in crawling.
Achat ina the waves of contraction do not take in the whole surface of the
sole (Fig. 2, X) : the pedal branches of the columellar muscle are strengthened
in the central field, and the lateral fields are moved in a vertical direction.
In other words, a preadaptation to the formation of a tripartite sole
(Fig. 2, from X to XI) is apparent here.

Thus (because of convergence) the pedal incisions are not suitable
for taxonomy on the level where they are most used. Even Pilsbry admitted
this when he recalled instances where the members of the Aulacopoda had
a holopod foot, and members of the Holopoda had an aulacopod foot (19^6:
231-232).

One conclusion which could be drawn from the data is extremely im-
portant for a further discussion, namely: the holopod type of foot in any
case will be the point of departure leading to the aulacopod. The latter

13

arises in those groups whose members are in need of rapid mobility : either
predators or slugs upon whose speed of movement depends the success in the
passive struggle against dessication.

lU

THE SEXUAL APPARATUS

The question regarding the appearance of the sexual apparatus in the
Geophila is of prime importance. As long as we assume that the Orthurethra
are the most primitive group, we must also assume the same for their sexual
systems. But the sexual apparatus of the orthiorethral Pupillina is speciali-
zed rather than archaic and cannot be regarded as the point of departure for
the other types .

If we leave aside the numerous cases of secondary simplification, then
the primary simple structure of the genitalia is foimd mostly in the primi-
tive Achatinina and Helixina: in the first case the Partulidae and Stropho-
cheilidae, in the second the Punctoidea (in the Pupillina and Oleacinina,
the most primitive forms do indeed possess appendages in the male portion).
Thus, the original type of the sexual system is extremely simple: from the
alhumen gland issues the spermoviduct (hermaphroditic duct) which then divides
into two parts, of which one is the seminal conductor (vas deferens) which
is longer than the vagina and forms a lateral loop. The spermatheca is
still not differentiated into a channel ( spermathecal duct) and reservoir
( spermathecal sac) and is represented only by an elongated sac off the vagina.

The longest appendage, the flagellum, is formed in a basic way (Fig. 3).
The first way is by moving the point where it enters into the seminal con-
ductor (vas deferens) below the epiphallus. The second mode comes about
by close contact of the distal part of the seminal conductor (vas deferens)
to the penis and the subsequent disappearance of the partition between these
channels. In general, it may be said that for the Pupillina and most Helixina
the first way is characteristic while the second is for the Achatinina and

15

Endodontinia.

In general, in the Achat inina, Endodontinia, and Limaxina the sexual
apparatus is close to the original type. But in the superfamily Achatinoidea
there is one peculiarity rarely seen in this suborder: the seminal conductor
(vas deferens) is in close contact with the penis and epiphallus and often is
joined to these channels, covered by a muscular connective tissue. In
r.ost Achatinina the cover is clearly seen in the lower part of the penis,
and in this case the seminal conductor (vas deferens) pierces the said cover
or passes below it (Araujo, 1973; Breure, 197^; Mead, 1950). Often —
and in various Helixina — a penial sheath is formed, but here the seminal
conductor (vas deferens) either remains free or is drawn to the atrial area
by sheaves and does not penetrate its own cover .

If we now turn to the Pupillina we see the unique genitalia of this sub-
order sharply delineated. The penis has two appendages (Fig. k) : a small
caecum and an appendix consisting of 5 sections. In a full view we distinguish:
1. a basal cylindrical, swollen section (Al); 2. a spherical section
separated from the base by a sphincter (A2); 3. a short, narrow cylindri-
cal structure (A3); ^. a thin tube with muscular walls (AU); 5. a widened,
lengthened ampule (A5) (Schileyko, 1976b). Based on this — and many authors,
without providing data, homologize the penial appendix with the stylophora
Cdart sac) and mucus glands of the higher Geophila (Albers, i860; Forcart,
19^0; Ihering l892; 1909; Wiegmann, 1900) — we must note that the appendage
fulfills a stimulating function before coitus. There is also the supposition
that the appendage is involved in the reception of the partner's spermato-
phore. As to the caecum, Forcart (19^0) ascribed to it the function of the
mechanical place of the retention of the spermatophore before copulation.

16

The fmiction of the epiphallus (and flagellum) is the same as in other
groups with spermatophores ; namely, the formation of a cover for the
latter.

It's easy to understand the role of the caecum when an individual with
the spermatophore still contained inside the penis is opened: the cover of
the latter has a "spur" formed in the cavity of the caecum corresponding to
the shape of the cavity. The spur apparently is,. an. anchor wbi.Gh_.preyeOts
the spermatophore from leaving the sexual system earlier than is necessary.
The spermatophore itself has a gutter or furrow "over" which is drawn a
thin film, but the film is absent in the posterior part (Fig. 5). In a
histological examination of individuals of some Buliminidae species,
collected immediately before copulation, sperm was detected inside A5 .
It is apparent that this could not be allosperm (sperm of the partner);
firstly, because coitus had not yet taken place, and secondly, because there
is a spermatheca for the reception of the allosperm. Consequently the
sperm noted was autosperm and thus A5 serves as a supplementary depot for
the autosperm where the latter enters before coitus and possibly there also
awaits the period of ripening.

To sum up, in an animal ready for coitus the sperm is collected inside
A5, and the spermatophore is formed already but it is empty. In copulation
the penis is twisted, Al and A2. The spermatophore is delivered to the partner,
and when the larger part of it has already left the penis, the sperm is forced
into the cavity of the spermatophore cover by contraction of the musculature
in A3 and aU . A2 serves as the regulator of the entrance of sperm into the
spermatophore since it is provided with one or two sphincters and papillae.

This is the situation in many Palearctic Pupillina. Extraordinarily

IT

interesting modifications of this type of genitalia appear in the Pacific
Achat inellidae (Cooke & Kondo, I960): in members of some groups there is
a substitution of the penial appendix, as a result of which the latter is
reduced.

To account for this modification of the male apparatus among Pacific
taxa, one expects to see some reduction of the penial appendix among Paleartic
families. Indeed, there is only a single family where this occurs: the
Orculidae (Schileyko, 1976b; Steenberg, 1925) — which in any case shows
a large degree of uniqueness in the organization of the male sexual structures.

Furthermore in the Geophila the presence of a more or less complicated
structure of the quadrivia is characteristic, in the composition of which
there is a fertilization chamber, a spermatheca and also incurrent and ex-
current channels (L. Schileyko and A. Schileyko. 1975; Flasar , 1967; Lind,
1973; Van Mol, 1971). As far as is known, the only group where the quadrivia
are represented simply by a bend of the hemaphroditic channel is the Partu-
lidae, and this bears witness to the primitiveness of this group when compared
to the other Geophila.

Once again we emphasize the fact that the simplest sexual apparatus
as a whole is found in Achatinina (Fig. 6) and thus this simplicity is of
a primary character. The most complicated element — the penial papillae —
is only seen from time to time in this group (Fig. 6, V) independently of the
formation of analogous structures in other suborders .

The sexual apparatus of the higher Helixina — Helixinia and Zonitinia
and also Limaxina has an entirely different aspect. In these taxa the primary
presence of vaginal appendages is characteristic — the sarcobelum, stylo-
phores or other appendages like the atrial gland in Milacidae. The most

18

commonly associated organs of the stylophores are the mucous glands although
at times the sarcobelum is also provided with glands.

It may be thought that all these appendages came about as a result of
a differentiation of non-specialized glandular tissue in the lower part of
the vagina, since their formation took place no fewer than 3 times: l)
when the h stylophores and mucous glands are arranged like a wreath around
the vagina (Humboldtianidae) ; 2) when the h stylophores are arranged in 2
rows (Hygromioidea) i in both cases the number of stylophores is reduced to
one; 3) the position of a single sarcobelum.

As for the male portion in the Helixinia, in the Endodontinia the
penis is simple, at times sac-like, often with internal appendages (Climo,
1969, 1970, 1971); Riedel and Wiktor, 197^; Solem, 1970). The only external
appendage — often absent — is the flagellum. The penis of the Helixinia,
especially in the Vitrinoidea, is more complex. Here, in addition to the
flagellum, there is also a caecum, not homologous to the caecum of the Pupil-
lina. In answer to the complicated shape of the spermatophore cover, the
cavity of the flagellum is also complicated. In a series of Recent forms,
one can trace the process of the simplification of the male portion through
the disappearance of the caec\im; the flagellum likewise shortens and may
be reduced, and the surface of the spermatophore is often also simplified.
In Pseudoaustenia ( Ariophantidae) the flagellum also disappears, but the in-
ternal surface structures, characteristic of the species, have an internal
epiphallus (Van Mol, 1973). Among various taxa of the Helixinia, as also
Eimong the Achatinina, the formation may be seen of a penial sheath (many
Euconulidae, Helicoidea, Vitrinoidea, etc.).

Finally there is one other important element in the male portion — the

19

penial papillae. Very often the papillae are present in the Helixinia, and
in some cases even 2 papillae are formed (Schileyko, 1972"b), but these may
appear independently in members of all the other taxa.

In conclusion we note that there are no characteristics in the sexual
apparatus sufficient to clearly differentiate 3 infraorders within the
Helixinia, even if we do not consider the reduction of characteristics which
may lead in time to a formal resemblance based on negative characteristics.
Thus several Helicoidea ( Oreohelicidae, Bradybaenidae) characteristically
have one stylophore on which the mucous glands are located; however, on the
external sarcobellum in Elaphroconcha (Ariophantidae) , k mucous glands are
similarly located.

We now proceed to the diagnostic characteristics of the suborders and
the infraorders, and we will also attempt to define their limits and size.

20

Order Geophila Ferussac, l8l2
Suborder Achatinina Schileyko, new

The shell is achatinoid, bulimuloid, or elongate-fusiform in shape with
columellar lamellae. Longitudinal parietal lamellae are absent or present
only in the last whorl; the aperture often lacks teeth. The sexual system
is without appendages except for a flagellum on the penis; often there is a
close connection of seminal duct (vas deferens) to the penis and a penial
sheath appears. The kidney is shortened with the urethras closed to differ-
ing degrees. The foot is holopod. Obligatory predators are not found in
the suborder. Oviparous, very rarely is ovoviviparity observed.

1. Superfamily Achatinoidea

(Megalobulimidae Leme, 1973, Strophocheilidae Thiele, 1926;
Odontostomidae Pilsbry et Vanatta, I898; Bulimulidae Tryon,
1867; Amphibulimidae Crosse et Fischer, l873; Anadromidae
Zilch, 1959; Achatinidae Swainson, l8i+0; Dorcasiidae Conolly,
1915; Acavidae Pilsbry, l895 ; Clavatoridae Thiele, 1926).

2. Superfamily Subulinoidea

(Subulinidae, Crosse et Fischer, l877; Ferussaciidae
Bourguignat , l883; Stenogyridae Wenz , 1923).

3. Superfamily Clausilioidea

(Megaspiridae Pilsbry, I90U; Urocoptidae Pilsbry et Vanatta,
1898; Clausiliidae Morch, lQ6h; Filholiidae Wenz, 1923).
h. Superfamily Par tulo idea

(Partiaidae Pilsbry, 1900 ).

21

Suborder Oleacinina Schileyko, new
For the most part the shell is elongate with columellar lamellae.
Longitudinal parietal lamellae are wanting though the aperture at times has
teeth. The female genitalia do not have appendages and in the male portion,
the penis is simple or with 1-2 appendages. The foot is holopod. These
obligatory predators are oviparous.

1. Superfamily Testacelloidea

(Spiraxidae Baker, 1955; Oleacinidae Adams, 1855;
Testacellidae Gray, 18A0)

2. Superfamily Streptaxoidea

(Streptaxidae Gray, 1860)

Suborder Pupillina Schileyko, new
The shell is bulimuloid, rarely depressed or microhelicoid with colu-
mellar lamellae. The parietal lamellae are characteristic and the aperture
often has parietal teeth. Female genitalia are without appendages and the
penis primarily has a caecum and appendix consisting of 5 sections. The foot
is holopod. With the exception of the Sagdoidea, there are no obligatory
predators in the suborder. Oviparous, very rarely ovoviviparous .

1. Superfamily Cerioidea

(Ceriidae Fleming, 1818)

2. Superfamily Achatinelloidea

(Dendropupidae Wenz, 1938; Achatinellidae Gulick, 1873;
Orculidae Pilsbry, 1918)

3. Superfamily Cionelloidea

(Amastridae Pilsbry, 1911, Cionellidae Clessin, 1879)

22

4. Superfamily Pupil loidea

(Pupillidae Turton, 1831; Buliminidae Clessin, 1879;
Chondrinidae Steenberg, 1925; Pyramidulidae Wenz, 1923;
Valloniidae Morse, 1864; Vertiginidae Fitzinger, 1833;
Strobilopsidae Pilsbry, 1918)

5. Superfamily Sagdoidea

(Thysanophoridae Pilsbry, 1926; Sagdidae Pilsbry, 1895)

Suborder Helixina Schileyko, new
The shell is flat to turbinate, often thin and translucent and without
columellar lamellae. There are no longitudinal parietal lamellae and the
apertural margin is simple or with teeth. The female portion of the geni-
talia and/or the atrium primarily bears variable appendages or is provided
with a perivaginal gland. The penis has a flagellum; there are often other
appendages on the male genitalia. The kidney is shortened, the primary
urethra is closed, the secondary urethra is either completely or partially
closed. The foot is holopod or aulacopod. Together with herbivores
there are some obligatory predators. Oviparous or ovoviviparous.

Infraorder Endodontinia Schileyko, new
The shell is depressed with a wide umbilicus and often with strong
radial sculpture. The aperture often has teeth. The genitalia are
simple with a more or less elongate vagina, at times with a glandular
section. The penial papillae are absent. The foot is holopod or aulaco-
pod.

23

1. Superfamily Punctoidea

(Endodontidae Pilsbry, 1894; Polygyridae Pilsbry, 1895;
Helicodiscidae Pilsbry, 1927; Punctidae Morse, 1864;
Pleurodiscidae Wenz, 1923; Systrophiidae Thiele, 1926)

2. Superfamily Thyrophorelloidea

CThyrophorellidae Girard, 1895)

Infraorder Helixinia Schileyko, new
The shell is flat to spherical with the umbilicus narrowed to varying
degrees. Radial rib-like sculpture on shell is exceptional and apertural
teeth are rare. The genitalia are complicated with a perivaginal gland,
sarcobellum, stylophores, or mucous glands with the latter usually connected
to the stylophores or the sarcobellum. Penial papillae are generally
present. The foot is holopod or aulacopod.

1. Superfamily Gastrodontoidea

(Euconulidae H.B. Baker, 1928; Gastrodontidae Tryon, 1866;)

2. Superfamily Rhytidoidea

(Rhytididae Pilsbry, 1893; Haplotrematidae H.B. Baker, 1925;
Chlamydephoridae Cockerell, 1935)

3. Superfamily Vitrinoidea

(Helicarionidae Bourguignat, 1888; Trochomorphidae
Mollendorff, 1890; Urocyclidae Simroth 1889; Ariophantidae
Godwin-Austen, 1888; Vitrinidae Fitzinger, 1833)

4. Superfamily Arionoidea

(Otoconchidae Cockerell, 1893; Arionidae Gray, 1840;
Phylomycidae Gray, 1847)

24

5. Superfamily Sphincterochiloidea

(Sphincterochilidae Zilch, 1959)

6. Superfamily Helicodontoidea

(Helicodontidae Hesse, 1918)

7. Superfamily Helicoidea

(Humboldtianidae Pilsbry, 1939; Helicidae Rafinesque, 1815;
Helminthoglyptidae Pilsbry, 1939; Bradybaenidae Pilsbry 1939;
Corillidae Pilsbry, 1905; Oreohelicidae Pilsbry, 1939;
Camaenidae Pilsbry, 1895; Ammonitellidae Pilsbry, 1930)

8. Superfamily Hygromioidea

(Hygroraiidae Tryon, 1866)

Infraorder Zonitinia Schileyko, new
The shell is depressed, zonitoid, with the umbilicus narrowed to
varying degrees; a clear tendency to shell reduction and slug form is
present. Sculpture is weak; apertural teeth are absent. The female portion
of the genitalia has a perivaginal gland or atrial gland. The penial
papillae are mostly absent or closed. The foot is aulacopod.

1. Superfamily Zonitoidea

(Zonitidae Mbrch, 1864; Daudebardiidae Pilsbry, 1908)

2. Superfamily Parmacelloidea

(Parmacellidae Gray, 1860; Milacidae Germain, 1930)

Suborder Limaxina Schileyko, new
The shell is represented by a plate or separate calcareous grains.
The female portion of the genitalia is without appendages; the penis is

25

likewise without appendages though at times a short flagellum is present.
The internal structure of the penis at times is very complicated. The
kidney is very variable and bears a relationship to the reduction of the
shell; the urethras are closed. The foot is aulacopod. These oviparous
animals are herbivores or predators.

Infraorder Trigonochlamydinia Schileyko, new
The mantle is small, most often without a hood and sharply posterior.
The penis^.is tube-like, smooth internally; spermatophores rest on glandular
pillows and their shapes do not correspond to the shape of the penis. Obli-
gatory predators.

1. Superfamily Trigonochlamydoidea
(Trigonochlamydidae Hesse, 1882)

Infraorder Limaxinia Schileyko, new
The mantle is well developed, with a hood most often on the anterior
part of the body. The penis is elongate or sac-like and spermatophores
are not present. Herbivores.

1. Superfamily Limacoidea

(Boetgerillidae Van Goethem, 1972; Limacidae Rafinesque, 1815;
Agriolimacidae Wagner, 1935)

26

PROBLEMS OF PHYLOGENESIS

From the data available it appears that in the Geophila there are two
basic phylogenetic branches: A) shell high, with columellar (and often with
parietal) lamellae; female genitalia without appendages. B) shell depressed,
without columellar parietal lamellae; female genitalia show an inclination
to the formation of various, at times very complicated, appendages.

The first group includes the Achatinina, Oleacinina, and Pupillina; in
the second are the Helixina and Limaxina. The apportionment, however, is not
into 2 but rather 5 suborders and this is clearly seen from the early diversi-
fication of the corresponding phylogenetic branches (Fig. 7).

Near the base of the first phylogenetic branch stands the Partulidae.
The reasons for thus placing the family are the following: the shell is
primitive, although it also has such progressive features as an absence of
parietal lamellae. The kidney is orthurethral, but one can already note the
differentiation into sac-like proximal and narrow distal divisions (Fig. 8B) .
The foot is extraordinarily archaic (see above). The sexual apparatus is
also extraordinarily and primitively simple (Fig. 8V); the simplicity is not
a result of the reduction of any appendages; the seminal tube (vas deferens)
is not connected directly with the penis and a penial sheath is lacking.
One may think that the progressive (derived) features of the Partulidae are
bound up with oviparity; individuals of the Partulidae from time to time
lay 1-2 relatively large eggs, the diameter of which we compare to the dia-
meter of the aperture of the mature mollusk. It is clear that when laying
eggs of such a size -- large enough to contain the developing young -- the
formation of any hard structures such as dentition in the aperture would be
hampering. Kondo fj Burch (1972) also emphasize the antiquity of the group.

27

These circumstances force one to see in the Partulidae a taxon which
is close to the basic common stem from which the Achatinina, Oleacinina, and
Pupillina were derived. The closer phyletic association of the Partulidae
especially to the Achatinina is based primarily on the sexual apparatus.
This is one of the arguments for regarding the Achatinina as the most primi-
tive suborder and not the Pupillina as is now believed.

This conclusion is confirmed by other arguments. Thus, in Achatinina,
in addition to Partulidae, there occurs an intensively developing process in
the formation of sigmurethry, beginning for the most part with the shortening
of the kidney. Beginning mesurethry in this way is a feature of the lower
Achatinina (Megalobulimidae, Strophocheilidae, etc.). There is also another
way: (of evolving sigmurethry) the closing of the urethra without noticeably
shortening the kidney (Antidrymaeus, Fig. 6G). Leme (1973) suggested that the
Megalobulimidae, proposed by him, is one of the most primitive groups of the
order, and this once again emphasizes the correctness of our view regarding
the systematic and phylogenetic placement of the Achatinina. The Megalobuli-
midae is the ancestor of the ancient form from which the Partulidae also
originated, but the Megalobulimidae is more progressive or advanced in the
structure of the kidney.

One can not doubt the unity of the conchologically strongly characterized
Clausilioidea, if one omits the fossil Filholiidae. But even the sinistral
Filholiidae already bear, in a weakly developed form, the features specifi-
cally peculiar to the Clausiliidae: an apertural fold and a clearly defined
sinulus. The similarity and the simple arrangement of the genitalia of the
Clausiliidae and Urocoptidae developed convergently and independently from the
Megaspiridae. If in Clausiliidae the development of the shell was by way of

28

strengthening the apertural armament, then in Urocoptidae it took place in
a basically different manner: through the differentiation of the columellar
lamellae. Moreover, the Urocoptidae is more progressive in the organization
of the excretory apparatus.

The shell of the Pupillina is more advanced in general features. The
following should be added. We propose the following points which diverge
even more from previous schemes and generally accepted opinions: 1) the
union in one superfamily of the fossil Dendropupidae, the eastern Mediter-
ranean Orculidae, and the Hawaiian Achatinellidae; 2) the introduction
into the suborder Pupillina of the Ceriidae and the superfamily Sagdoidea.

To the first of these two points the following considerations should
be stated. Knight (Moore, 1960) places Dendropupidae in the Cyclophoridae
together with 2 other genera. However, it is obvious that as a matter of
fact Dendropupa properly belongs with the Geophila and is not related to
Maturipupa and Anthracopupa. Therefore, when we speak of the Dendropupidae
we have only the real Dendropupa in mind. Thus, the families Dendropupidae,
Orculidae, and Achatinellidae are united by the shape of the shell and,
most fundamentally, by the presence of well developed parietal lamellae
running from the first whorl to the last. As for the internal features,
the Orculidae and the Achatinellidae are the only Pupillina in which
the variations of the copulatory apparatus can not easily be ascribed simply
to a reduction of the penial appendix or the origin of small partial changes,
but they bear a 'creative' character; i.e., different elements are developed;
they alter the surface appearance and the internal structure, and by no
means are they cast in the static mold as in the other Pupillina [cf. Cooke
5 Kondo, 1960; Schileyko, 1976b). Therefore, although one can not speak of

29

an immediate closeness, there are some reasons to place them in the same
superfamily, Achatinelloidea.

As for the Ceriidae (Fig. 9), the open secondary urethra testifies
to the definite primitiveness of the group; the case of the sexual appara-
tus is somewhat more complicated. Firstly, the presence of a diverticulum
in the sperraatheca is for the Pupil lina much more characteristic here than
for the other groups. Secondly, the support or attachment of the penial
retractor muscle to the flagellum or penial appendix, (Fig. 9, PA), is a
rare phenomenon and occurs only in aberrant species of the higher Geophila.
From this it follows that the long appendage to which the retractor in Cerii-
dae is fastened is apparently the rudiment or derivative of the penial ap-
pendix. If this is true, then the family must be placed in the Pupillina.
If one tries to find a place for the Ceriidae outside the Pupillina, this
must be only with the Achatinina. At the same time the unique Ceriidae
must be separated into a monotypic superfamily, the Cerioidea.

In regard to the Sagdoidea we must say that there are two serious
objections to including them in the Pupillina: the depressed shell and the
sigmurethran type of excretory apparatus. Actually the depressed shell
is not typical in the Pupillina; the flat shell of Hendersoniella does not
prevent the association of that genus with the Urocoptidae and the cylindri-
cal Cylindrus is associated with the Helicidae. In addition, there exists
the possibility of associating the strongly flattened shell of the type
of the sagdid Lacteoluna with the high shells of the Pupillina by way of
the high cupola-shaped shells of the West Indian Sagda. As for excretory
apparatus, one may determine that the secondary urethra in different groups
is not completely closed, and the length of the kidney in the Sagdoidea

30

is 2-3 times longer than the pericardium and takes in almost half the roof
of the mantle cavity; in other words, the Sagdoidea is not so greatly dif-
ferent from the other Pupillina in this respect. In this connection it
is necessary to take into account the fact that all Sagdoidea are predators
and such a life style always strongly stimulates the formation of sigmurethry.

At the same time the presence of a penial appendix is characteristic of
the Pupillina, and moreover, only the Pupillina. Some Sagdoidea (e.g. Lacteo-
luna) have an appendix of sufficiently typical structure (Pilsbry, 1940) .

Let us pass on to an examination of the suborder Oleacinina. This taxon,
overlooking for the moment the great conchological variability of the Strep-
taxidae, has a sufficiently characteristic shell and a spiral columellar
lamella.

Here it is necessary to digress and once again strongly emphasize the
fact that if we take into account all modifications of shell shape (in this
case for the Streptaxidae) , it would be impossible to establish a differential
diagnosis for most families or for that matter the majority of the genera
of the Geophila, not to mention taxa of higher rank. Therefore, schematic
generalization is always unavoidable. When one mentions the name of any
taxon there appears in the mind of the reader not some kind of definite pic-
ture, but rather a sort of generalized image of a shell shape which neverthe-
less contains most of the characteristic features of the taxon as a whole.
Such a generalized picture nevertheless presents a very real idea of the
group. We had such considerations in mind when we added figures of the
shells in Figure 7.

Let us return to the examination of the Oleacinina. This suborder,
in spite of all the variations of the shell, is quite compact. The repro-

31

ductive systems of the Spiraxidae and the Streptaxidae do not differ greatly
and the chitinous hooks which occur inside the penis in several Streptaxidae
are doubtlessly later derived acquisitions.

The generally simple structure of the distal portions of the sexual
system is characteristic for all Oleacinina. The only complication in the
Oleacinidae, for instance, is the presence of one -- rarely two -- sac-like
growths on the penis (Fig. 10); in some of the Streptaxidae a penial appendage
may also be present.

Let us proceed to the higher suborders --Helixina and Limaxina. First
of all we must point to the widely held erroneous opinion that the Helicidae --
more definitely the genus Helix --represents the highest development of the
Geophila. The slugs without doubt are the biologically most progressive
shell-bearing raollusks, since the shell itself is a hindrance to biological
advance, because any external stimulus brings forth a single stereotyped
reaction: the animal pulls back into the shell. The mollusks without a shell
must move more rapidly and possess a certain level of neural organization in
order to react adequately to any kind of stimulus. Such was shown by Zs.-Nagy
§ Sakharov [1970) who found a much stronger development of the web of synapses
in the procerebrum of Limax than in Helix. This is further exhibited in the
fact that in many slugs or semi-slugs there is a tripartite division of the
sole which insures a greater speed of movement. Of course, this does not
mean that such a sole is a necessary diagnostic feature of this group.

In Fig. 7, the infraorder Endodontinia is treated like the main (stem)
group in relationship to the other Helixina. This treatment is supported by
the following facts and considerations. The shell of the Endodontidae and
related groups is little specialized and may be regarded as the origin of

32

almost all the conchological types of the higher Geophila. The foot is holo-
pod, the kidney sigmurethran, although in several Helicoidea the secondary
urethra may be partially or completely closed (Schileyko, 1976a; Wurtz, 1955) .
The sexual apparatus has a primary simple structure, and it is precisely on
account of that low level of specialization that the ancient Endodontinia
proved to be so plastic that they provided the origin of the phylogenetic
branch of the three infraorders here delineated. The basic directions of
specialization may be characterized as follows:

1. A tendency to decreasing the parameters of the shell, seen for
the most part in the groups from the temperate latitudes of both hemispheres
(the Punctidae and the Helicodiscidae) together with the retention of a
simple sexual apparatus.

2. The complication of the apertural margin because of the formation
of dental armature (the Polygyridae and certain specialized tropical Endo-
dontidae) . The erection of this taxon is not correlated vidth any complication
of the sexual apparatus.

3. The gradual reduction of the shell with a parallel significant
complication of the male and female genitalia. This tendency can be seen
in the many Helixina (the Gastrodontoidea and the Vitrinoidea) . In other
instances the reduction of the shell is not accompanied with any significant
complication of the genitalia (most Zonitinia) .

There are three small groups related to the ancient Punctoidea whose
precise systematic position is still problematic. First there is the mono-
typic family Thyrophorellidae. The sole genus of the family with its unique
sinistral shell has the upper part of the aperture strongly projecting ante-
riorly and this part is semi -moveable attached to the rest of the shell.

33

The genitalia cast no light on the provenance of this group because of their
simple structure; the only feature which is worthy of attention is the long,
slightly fusiform vagina which is characteristic for many lower Endodontinia.
Boettger (1962) suggested that this group should be associated with the Ario-
phantoidea (i.e., in our opinion, Vitrinoidea) ; however, the complicated
organization of the sexual system of the latter is characteristic, and we,
therefore, follow Thiele (1931) and prefer to place the Thyrophorellidae
in the Endodontinia, establishing for it a separate superfamily to emphasize
its uniqueness.

The second group of debatable systematic placement is the Pleurodisci-
dae. At present the family is unanimously placed with the lower Orthurethra
(essentially the Pupillina) for the reason that in Pleurodiscus both urethras
are open. However, this feature should not serve as a criterion for such
a high taxonomic level. The simplicity of the genitalia of Pleurodiscus
is primary although such a reduction of the complicated characteristics of
the Pupillina, aside from the specialized Vertiginidae, does not attain the
state of terminal attachment for the sexual retractor muscle as occurs in
Pleurodiscus; this feature is quite characteristic for many Endodontinia.
As for the shell, it is of the type near the one which is conceivably or-
ginal for the Helixina. All the non-bulimuloid shells of the Pupillina
have a diameter not greater than 3-4 mm for reasons discussed above. At
the same time the shell of Pleurodiscus reaches 15 mm in width. Finally
it is not out of place here to put the question: what in general associates
Pleurodiscus with the Pupillina aside from the formal resemblance in the
structure of the renopericardial complex? One can only answer this question:
nothing .

34

From these reasons we consider the family to be one of the lowest mem-
bers of the suborder Helixina which retained the orthurethran type of ex-
cretory apparatus .

A third familial group questionably included in the Endodontinia is
the Systrophiidae. The shell has a typical endodontid appearance. The
sexual system lacks appendages and an epiphallus is not marked. Character-
istic is the terminal attachment of the sexual retractor muscle; in other
words, the Systrophiidae are typical members of Endodontinia. Nevertheless
they are always associated with the typically predatory families (the Zoniti-
dae and the Trigonochlamydidae) . However, the predatory specialization takes
place in various taxa of the Geophila, and one can observe its independent
origin in several lineages. The Endodontinia constitute no exception.
Naturally the change to the predatory condition is accompanied by correspond-
ing changes in the structure of the radula, foot, and renopericardial
complex.

Solem (1975) has convincingly shown that the Helicodiscidae should be
an independent family.

Among the Helixinia the only obligatory predators are the Rhytidoidea
reflected also in their outer appearance. Further, this is also one of the
rare cases when the predator has a non-aulacopod foot. Nevertheless the char-
acter of the mobility of these animals deserves a thorough investigation,
(cf. supra. Fig. 3, VI-VII).

In Fig. 7 it is seen that the Euconulidae and the Gastrodontidae are
removed from the Zonitidae and associated as the Gastrodontoidea with the
Vitrinoidea. Their removal from the Zonitidae was explained earlier (Schileyko,
1972a). There are no serious objections to the placement of these families

35

near the Vitrinoidea (Van Mol and Van Bruggen, 1971; Verdcourt, 1960).
Moreover, the association of the Helicarionidae with the Vitrinoidea is
confirmed by the fact that in the Vitrinid genus Semilimax there is a sarco-
belum of characteristic structure (Hubendick, 1953 and our own data).

The organization and the phylogeny of the higher Helixinia --Helicoi-
dea of authors -- has already been considered (Shileyko, 1978). Therefore, -
we will confine ourselves to the main points here. Basically it must be
emphasized that it is impossible to associate the Helicoidea and the Hygromioi-
dea to one another on anything but superfamilial grounds. Thus, if we
were to take the most archaic groups among these taxa, namely the Humboldtiani-
dae and Trichiinae, we would discover two distinctly different methods of
the placement of the stylophores (Vide supra) . There is another sharp dif-
ference between these superf ami lies.' in the Helicoidea, the reservoir of
the spermatheca is connected by bodies of connective tissue to the bottom
of the mantle cavity and presses into the base of the albumen gland: in
the Hygromioidea the spermatheca is not bound up with the mantle cavity
but is joined to the spermoviduct .

The Helicodontoidea apparently is a heterogenous group and at pre-
sent it is difficult to determine its phylogenetic connections. One may
only" note that there are four types of sexual systems (Helicondonta, Lind-
holmiola, Oestophora, and Mastigophallus) whose phyletic succession cannot
be traced. The shell alone unites them in one superfamily -- flat, multi-
whorled, with reflected apertural margins.

The organization of the Sphincterochilidae has been discussed often
(Schileyko, 1972b; Forcart, 1972a, b) ; the unique structure of the foot
and the sexual apparatus has been emphasized as reflecting a considerable

36

distinction of the family from other helicoid groups. At the same time the
association of the Sphincterochilidae with the Helicoidea is not in doubt.
This is due most of all to the typically helicoid shell of Sphincterochili-
dae which only too clearly relates the group to the Helicoidea. Nevertheless,
if one were to disassociate oneself from the prejudice exerted by external
appearance and compare the sexual system of the Sphincterochilidae with the
genitalia of the Vitrinoidea, it is not difficult to see how the Sphinctero-
chilidae naturally fits into a scheme more closely related to vitrinoids
than to the helicoids; the sarcobelum is armed with a mucous gland; the
penis has a sac-like appendage and a flagellum (cf. Solem, 1960; Van Mol,
1968, 1970, 1973). The low degree of specialization of the sexual appara-
tus in the Sphincterochilidae forces one to see it as a group close to
the ancestral form of the Vitrinoidea though still noticeably divergent.
In the Vitrinoidea, the tendency to shell reduction is characteristic. The
higher members of the superfamily are already slugs or semi-slugs. The lower
Vitrinoidea have well developed shells, and the ancestors of Sphinctero-
chilidae, possessing a normal shell, adapted to living in arid conditions;
their development was directed toward the thickening of the shell walls and
the formation of other adaptive features (i.e. white color and sharply nar-
rowed aperture) .

The infraorder Zonitinia derived independently from the Helixina
from ancient Endodontinia and are clearly separable into two superf amilies :
1) Zonitoidea, in which the process of shell loss can be observed as the
lineage turns predatory; and 2) the Parraacelloidea which completely or parti-
ally loses the shell in going from herbivorous to omnivorous.

The peculiarities of the organization of the suborder Limaxina,

37

composed exclusively of shell-less forms, has been discussed by Likharev
5 Victor (1979).

In summary, in examining the evolutionary paths in the suborders
and infraorders, one may note the following lines of specialization and de-
velopment of different organs and structures which appeared independently
and convergently in all taxa,

1. The appearance of sigmurethry with complete closing of the urethra.

2. The formation of the aulacopod foot often accompanied by the ap-
pearance of a tripartite sole.

3. The reduction of the shell and the evolution of the slug form.

4. The transition to a predatory state; this process was often associ-
ated with the elaboration of a higher direction of specialization.

Acknowledged is the criticism and help given the author by N. N. Akramovski,
Ya. I. Starobogatov and I.M. Likharev.

38

LITERATURE
Russian Titles

Likharev, I. M. 1962. Mollusks - Clausiliidae , Faiina USSR, new series,

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Likharev, I. M. and A. I. Viktor. 1979. Parallelism in the structiore

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CinI! The morphology, systematics, and phylogeny of mollusks. Trudy

Zoologicheskogo Instituta, Akademiya Nauk SSSR (Transactions of the

Zoological Institute, Academy of Sciences, USSR). 8O: 70-86.
Minichev, Yu. S. 1971- The position of Soleolifera in the systematics

of Gastropoda. CinU Mollusks, path, methods, and summary of their

study. IV. Nauka, Leningrad (section), Leningrad, pp. 8-10.
Minichev, Yu. S. and Ya. I. Starobogatov. 1975- On the structure of

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and role in nature. V. Nauka, Leningrad (section), Leningrad, pp. 8-11.
Minichev, Yu. S. and L. V. Slavoshevskaya. 1971. Features of the evolution

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50: 350-360.
Slavoshevskaya, L. V. 1971- On the systematic position of Succineidae.

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Schileyko, A. A. 1967. On the factors of change in several terrestrial

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Biologiya, Pochvovedenie (Herald of Moscow University, Moscow,

ser. 6, Biology, Soil Science), no. 2. pp. 1^-21.

39

Schileyko, A. A. 19T2a. The organization of Zonitoides nitidus (Miill.)
in connection with the problem of the taxonomic rank of the Gastro-
dontidae (Gastropoda, Styleimnatophora) . Trudy Zoologicheskogo
Museya, Moskovskogo Gosudarstvennogo Universiteta (Transactions of
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Schileyko, A. A. 1972Td. Several aspects of the study of Recent contin-
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hespozvonochnykh (Invertebrate Zoology). 1: I-I88.

Schileyko, A. A. 19T6a. The paths of evolution of the excretory

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Schileyko, A. A. l9T6b. Features of the organization and systematics

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Schileyko, A. A. 1978. Mollusks of the superfamily Helicoidea of the
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sect. 6: I-38I+.

Schileyko, L. V. and A. A. Schileyko. 1975- On the morphology of the

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Pulmonata). Nauch . dokl. vyssh. shkoly. biol. nauki (Scientific
reports of the higher educational school for biological sciences),
no. 1. pp. 7-13-

UO

Non-Russian Titles

Alters, J. C. i860. Die Heliceen nach naturlichen Verwandtschaft systemati-
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pp. 1-359.

Araujo, B. J. L. de. 1973. Superfamilia Bulimulacea do Brasil Odontostomi-
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Baker, H. B. 19U1. Outline of American Oleacininae and new species from
Mexico. Nautilus. 55: 5I-61.

Baker, H. B. 1955. Heterurethrous and aulacopod. Nautilus. 68: 109-112.

Baker, H. B. 1962. Puerto-Rican Holopodopes. Nautilus. 75: 116-121.

Boettger, C. R. 195^. Die Systematik der euthyneuren Schnecken. Verhl.
deutsch. Zool. Gesell. Tubingen, pp. 253-280.

Boettger, C. R. 1962. Gastropoden mit zwei Schalenklappen. Verb, deutsch.
Zool. Gesell. Tubingen, pp. U03-U39.

Breure, A. S. H. 197U. Notes on the genus Gaeotis Shuttleworth, 185U.

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Climo, F. M. 1969. Classification of New Zealand Arionacea (Mollusca:

Pulmonata). II. A revision of Charopa subgenus Ptychodon Ancey, I888.
Rec. Dominion Mus . Wellington. 6: 175-258.

Climo, F. M. 1970. Classification of New Zealand Arionacea (Mollusca:

Pulmonata) . III. A revision of the genera Charop_a Albers , i860 (exclud-
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Mus. Wellington. 6: 285-366.

Climo, F, M. 1971. Classification of New Zealand Arionacea (Mollusca:
Pulmonata) . IV. A revision of the subfamily Otoconchinae Cockerell
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Ul

Cooke, C. M. and Y. Kondo . I960. Revision of Tornatellinidae and

Achatinellidae (Gastropoda, Pulmonat a ) . Bull., Bernice P. Bishop

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Flasar, I. 1967. Der innere Bau der Befruchtungstasche bei Oxychilus

draparnaudi (Beck) und die Geschichte ihrer Entdeckung und Erforschiing

bei anderen Pulmonaten. Vestn. Ceskoslov. spol. zool. 31: 15O-I58.
Forcart, L. 19^0. Monographic der turkischen Enidae (Moll. , Pulm. ) .

Verhandl. Naturf. Ges . Basel. 51: 106-263.
Forcart, L. 19T2a. Le sous-genre Cariosula Pallary du genre Sphinctero-

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Forcart, L. 19T2b. Systematische Stellung und Unterteilung der Gattung

Sphincterochila Ancey. Arch. Moll. 103: IU7-16U.
Hubendick, B. 1953. The relationships of the East African Vitrinae with

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Ihering, H. 1892. Morphologic und Systematik des Genitalapparatus von

Helix. Zeitschr. Wiss. Zool. 5^: 386-U33; U25-520.
Ihering, H. 1909. System und Verbreitung der Heliciden. Verb. Zool.

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Kondo, Y. and J. B. Burch. 1972. Archaic land snails of the Pacific

islands. Malac . Review. 5: 17-18.
Leme, J. L. M. 1973. Anatomy and systematics of the Neotropical Stropho-

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i+2

Mead, A. R. 1950. Comparative genital anatomy of some African Achat inidae

(Pulmonata). Bull. Mus . Comp. Zool. Harv. Coll. 105: 219-291.
Moore, R. C. (ed.). i960. Treatise on invertebrate paleontology. Part I,

Mollusca, 1. Geol. Soc. Amer. Univ. Kansas Press; New York. pp. 1-351.
Pilsbry, H. A. 1900. On the zoological position of Partula and Achatinella.

• Proc. Acad. Nat. Sci. Philad. 52: 561-56?.
Pilsbry, H. A. 19U0. Land Mollusca of North America (north of Mexico).

1, part 2. Monogr. Acad. Nat. Sci. Philad. 3: 575-99^.

Pilsbry, H. A. 19I46. Land Mollusca of North America (north of Mexico).

2, part 1. Monogr. Acad. Nat. Sci. Philad. 3: 1-520.

Riedel, A. and A. Wiktor. 197^- Arionacea. Slimaki krazalkowate i

slimakowate (Gastropoda: Stylommatophora) . Fauna Poloniae. 2.

Warszawa. pp. 1-lUO.
Solem, A. 1959. Systematics and zoogeography of the land and freshwater

Mollusca of the New Hebrides. Fieldiana: Zoology. U3: 1-359-
Solem, A. 1966. Some non-marine mollusks from Thailand, with notes on

classification of the Helicarionidae . Spolia Zool. Mus. haun.

Copenhagen. 2U: 1-112.
Solem, A. 1970. The endodontid land snail genera Pilsbrycharopa and

Paryphantopsis (Mollusca: Pulmonata) . Veliger. 12: 239-26^+.
Solem, A. 1975. Polygyriscus virginianus (Burch, 19^7) a helicodiscid land

snail (Pulmonata: Helicodiscidae) . Nautilus. 89: 8O-86.
Steenberg, C. M. 1925. Etudes sur I'anatomie et la systematique des Maillots

(fam. Pupillidae) . Vidensk. Medd. Dansk naturh. Foren. 80 : l-2l6.
Sullivan, J. T. and Th . C. Cheng. 197*+. Structure and function of the

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U3

Taylor, D. W. and N. F. Sohl. 1962. An outline of Gastropod classification.

Malacologia. 1: 7-32.
Thiele, J. 1931. Handbuch der systematischen Weichtierkunde. 1, Th. 2.

Jena. pp. 377-778.
Van Mol, J. J. 1967. Etude morphologique et phylogenetique du ganglion

cerebroide des Gasteropodes Pulmones (Mollusques ) . Mem. Acad. roy.

Belg. ,37. 5: 1-168.
Van Mol, J. J. 1968. Notes anatomiques sur les Helicarionidae (Gasteropodes

Pulmones). I. Etudes des genres Macrochlamys , Parmarion et Xesta.

Ann. Soc. roy. Zool. Belg. 98: 189-215.
Van Mol, J. J. 1970. Revision des Urocyclidae (Mollusca, Gastropoda,

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Mus. Roy. de I'Afrique centrale — Tervuren, Belg., Ann. Sci . Zool. l80: 1-23^
Van Mol, J. J. 1971. Notes anatomiques sur les Bulimulidae (Mollusques, Gas-
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Van Mol, J. J. 1973. Notes anatomiques sur les Helicarionidae , (Mollusques,

Gasteropods, Pulmones). II. Etudes des genres Pseudaustenia , Dyakia,

Helicarion et comprenant la description de Papuarion, genre nouveau.

Discussion sur la classification des Helicarionidae et les affinites

des Urocyclidae. Ann. Soc. roy. Zool. Belg. 103: 209-237.
Van Mol, J. J. and A. C. Van Bruggen. 1971. Description d'un nouveau genre

d'Euconulidae d'Afrique et discussion sur les affinites systematiques de

cette famille (Mollusca, Gastropoda, Pulmonata) . Rev. Zool. Bot . Af r .

8U: 285-296.
Verdcourt, B. 196O. Observations of the generic relationships of several

small East African Helicarionidae. J. Conchyl. 100: 107-117.

1+U

Wiegmann, F. 1900. Binnen-Mollusken aus Westchina und Centralasien.

1. Die Heliciden. Ann. Mus . Zool . St. Petersb. 5: 1-186.
Wurtz, C. B. 1955. The American Camaenidae (Mollusca: Pulmontata) . Proc .

Acad. Nat. Soc . Piiilad. 10?: 99-1^3.
Zilch, A. 1959-1960. Gastropoda, Theil 2: Euthyneura. CinD Handbuch der

Palaozoologie, 6. Berlin. I-XIlT^l-83i+ .
Zilch, A. 1961. Die Typen und Typoide des Nat ur -Museums Senckenberg,

2ii: Mollusca, Streptaxidae. Arch. Moll. 90:79-120.
Zs.-Nagy, I. and D. A. Sakharov. 1970. The fine structure of the procerebrum

of pulmonate molluscs, Helix and Limax. Tissue a. Cell. 2: 399-^11.

h5

Fig. 1 Comparative shell volume occupied by the molluscan
body (darkened) in regard to the extent of the umbilicus. The
shells have the same proportions and the same contours.
A. Widely umbilicate B. narrovly umbilicate.

Fig. 2 The types of placement of the grooves in the foot of
the Geophila.

I) from under the buccal flap extend a few short suprapedal
grooves (Partula)

II) the same type (Placostylus, Helicophanta, Urocoptidae)

III) only peripedal grooves ( Cerion, Oleacina, Paryphanta,
Helix, Subulinidae, Clausiliidae)

IV) suprapedal and peripedal grooves (sic) (the author means
with one pair of pedal grooves and one pair of suprapedal
grooves (Nesovitrea and Cecilioides )

V) two pairs of suprapedal and one pair of pedal grooves.
(Macrochlamys, Vitrina, Oxychilus , Trigonochlamys , Limax)

VI) one central pedal groove (Rhytida)

VII) one central pedal groove and a pair of suprapedal
grooves (Zonitoides )

VIII ) a pair of suprapedal grooves (Vitrea)

IX ) two pairs of suprapedal grooves (Discus , Arion)

X) groove absent, but waves of locomotor contractions pass
only along the central part of the sole (Achatina)

XI) hypothetical variant of the appearance of pedal grooves

at the expense of the differentiation of the central field.

Incisions in II-XI made on the level indicated by dashed line in I.

B

Figure 1

Figure 2

Fig. 3. Two methods of flagellum formation

I-IV) The descent of the seminal duct (vas deferens) distally.

V-VIII) The junction of the lower end of the seminal duct (vas-
deferens) with the apical part of the epiphallus.

Fig. h. Schematic representation of the male sexual section of Pupillina.
A1-A5 - parts of the penial appendix
PR - sexual or penial retractor muscle
F - flagellum
C - caecum

VIII

Figure 3

Figure h

Fig. 5- External view and form of the sperraatophore in Pseudonapaeus
albipliciatus (Mts.) (Pupillina, Buliminidae) above — a sperraatophore
taken from the spermatheca; below — the epiphallus and cross section
through the "tail" of the sperraatophore. The walls of the sperraatophore
shown in sections.

Fig. 6. The reproductive system and its structural details in
different Achatinina.

A - Placostylus shongi (Less.) from New Zealand (Bulimulidae) ;

the reproductive system and with penis opened

B - Antidrymaeus inusitatus (Fult.) from Brazil (Orthalicidae) ;
(Orthalicidae not separated from Bulimulidae) the reproductive
system and the partially opened spermatheca

V - the same with the penis opened

G - the same showing the organs of the mantle cavity

D - Helicophanta magnifica (Per.) from Madigascar (Acavidae); the
reproductive apparatus and the opened penis

E - Rumina decollata (L.) from Algeria (Subulinidae) ; with
the reproductive apparatus and the opend penis

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Fig. 8. Partula otaheitana (Brug. ) from Tahiti, Tahita-nua.
A - external view of the soft parts taken from the shell
B - organs of the mantle cavity
V - reproductive system

G - part of the herraaphoroditic duct and quadrivia or ferti-
lization chamber
D - penis opened
SU - secondary urethra
RV - respiratory vein
K - kidney
R - rectum
RS - rectal sinus

Fig. 9. Cerion glans (Kust.) from Cuba.
A - reproductive apparatus
B - quadrivia or fertilization chamber
V - atrial section of the genitalia

G - roof of the mantle cavity and cross section of the kidney
PA - penial appendix
AV - atrial valve
AM - atrial muscle

DS - diverticula of the spermatheca
RV - respiratory vein
K - kidney

PU - primary urethra
R - rectum
S - spermatheca

Fig. 10. Oleacina solidula (Pfr.) from Cuba. Left - reproductive
system and cross sections through uterus and vas deferens. Center - penis
in the region of its appendages, opened. Right - organs of the mantle cavity,

DPA - distal penial appendage

PPA - proximal penial appendage

SU - secondary urethra

K - kidney

PU - primary urethra

RO - renal orifice (orifice of primary urethra)

S - spermatheca

E - epiphallus

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